I'll never agree with this argument. If a player is one of your biggest threats and is capable of playing 80 then you play him 80. This "play him off the bench impact" is such a poor argument these days. If he ends up on the bench it should be because he's versatile enough to play through the middle and the blokes on the edge are doing a good enough job that the teams overall performance improves with him in that role.
What!
What if “one of your biggest threats” can’t be one of your biggest threats for the full 80 minutes?
What if he’s an even bigger threat when used in 2 high insensity bursts of, say, 20 minutes?
What if the opposition visibly tires after, say, 30 minutes and you need an impact player to then come on and tear ‘em up?
What if the opposition is strong up the middle, but they have to pace themselves to last 40 minutes?
What if they are then vulnerable to a wide running back rower?
What if the opposition’s half plays wide in defence after 25 minutes and you need a running backrower to aim up at him in offence?
What if ............... there are so many scenarios where having an impact player (whatever that impact is) on the bench ready when you need him is solid strategy.
Go Dogs